# Propagated Error Estimates of EGM2008

*Introduction*

*Introduction*

The official Earth Gravitational Model EGM2008 has been publicly released by the NGA EGM Development Team. This gravitational model is complete to spherical harmonic degree and order 2159, and contains additional coefficients extending to degree 2190 and order 2159.

Below is a set of files containing global 5' X 5' grids of propagated error estimates from EGM2008. The propagated standard deviations corresponding to point values of Free-Air Gravity Anomalies, point values of Height Anomalies/Geoid Undulations, and point values of the Deflection of the Vertical (DOV) components are included, along with a FORTRAN program to read the files. In all cases, the values in the files refer to the surface of the reference ellipsoid, and represent the spectral bandwidth from harmonic degree 2, to harmonic degree and order 2159, since this is the spectral bandwidth associated with the 5' X 5' gravity anomaly data that were used in the development of EGM2008. These data files were computed on a computer that uses **BIG ENDIAN** internal binary representation. If you need to convert these files to small endian representation, please visit our Binary File Conversion link where we provide a utility program that may be used for this conversion (with minor modifications). For further details and statistics of the data, please read the README file below.

Also, before using any of the data files on this web page, please read the disclaimer.

### Global Grids of EGM2008 Propagated Error Estimates

- README (README_FIRST.pdf) - File describing the content and structure of the files containing the EGM2008 propagated error estimates, and provides the statistics of their values.
- 5 x 5-Minute Free-Air Gravity Anomaly Error Estimate Grid (Dg_sig.s2-2159.Dg=v032608b.wt=v032308a.mGal_5 - 37 MB) - Global grid of EGM2008 propagated standard deviations corresponding to point values of free-air gravity anomalies in mGal.
- 5 x 5-Minute Height Anomaly/Geoid Undulation Error Estimate Grid (N_sig.s2-2159.Dg=v032608b.wt=v032308a.cm_5 - 37 MB) - Global grid of EGM2008 propagated standard deviations corresponding to point values of height anomalies/geoid undulations in cm.
- 5 x 5-Minute DOV Meridional Component (xi) Error Estimate Grid (xi_sig.s2-2159.Dg=v032608b.wt=v032308a.asec_5 - 37 MB) - Global grid of EGM2008 propagated standard deviations corresponding to point values of the meridional component (xi) of the DOV in arc-seconds.
- 5 x 5-Minute DOV Prime Vertical Component (eta) Error Estimate Grid (eta_sig.s2-2159.Dg=v032608b.wt=v032308a.asec_5 - 37 MB) - Global grid of EGM2008 propagated standard deviations corresponding to point values of the prime vertical component (eta) of the DOV in arc-seconds.
- Program to Read the 5-Minute Error Estimate Grids (read_4files_min05 - 8 KB) - FORTRAN program that can be used to read the EGM2008 propagated error estimate grids above.
- Output from the Program Above (read_4files_min05.out01 - 12 KB) - Contains the output from a run of the program above.

### Additional Information

- The development and evaluation of the Earth Gravitational Model 2008 (EGM2008) - Nikolaos K. Pavlis, Simon A. Holmes, Steve C. Kenyon, John K. Factor; Journal of Geophysical Research: Solid Earth (1978-2012) Volume 117, Issue B4, April 2012
- EGM2008 JGR Erratum
- An Earth Gravitational Model to Degree 2160: EGM2008 (NPavlis&al_EGU2008.ppt - 18.5 MB) - Presentation given at the 2008 European Geosciences Union General Assembly held in Vienna, Austria, April13-18, 2008.
- Background Papers from Earlier Symposiums on the New EGM

**Please provide comments, suggestions, and feedback to the contacts below as we strive to improve our EGM2008 products. Thank you!**

Dr. Nikolaos Pavlis NGA, Geodesy and Geophysics Basic and Applied Research wgs84@nga.mil Nikolaos.K.Pavlis@nga.mil |
NGA Office of Geomatics (SN) EGM2008 Development Team wgs84@nga.mil |

Document last modified April 29, 2013